Femtosecond pump-probe experiments on rhodopsin are elucidating the mechanism of the first step in vision, which is a 200 femtosecond cis-trans isomerization of the retinal moiety of the protein. Anisotropy techniques are being used to study the reorientation of the retinal backbone during the reaction. Visible pump/ infrared probe techniques are being used to further study structural issues related to retinal motion. In this context, especially important will be probing of hydrogen-out of plane vibrations, which are very sensitive to backbone conformation of the retinal. Also, protein vibrational modes are being investigated as indicators or protein group involvement in the chemical process. To better characterize the potential energy surface of the reaction, absorption and emission spectra of the first reaction product, bathorhodopsin, are being recorded over an extended wavelength region. Based on all these measurements we are developing a coherent picture of the factors affecting this key reaction in visual phototransduction.